• intestinal microbiology
• diabetes mellitus
• enteric bacterial microflora
• colonic microflora

A growing body of evidence shows that the alteration of gut microbiota is involved in the pathogenesis of both autoimmune and metabolic disorders. This connection is straightforward, as human gut microbiota is known to shape the immune system and regulate the metabolism during early life, so its imbalance is expected to breach the homoeostatic healthy state and be a potential driver of disease. Based on this background, the increasing prevalence of both autoimmune and metabolic disorders worldwide has been hypothesised to be potentially caused by the progressive depletion of human gut microbiota that are associated with modern Western lifestyle.1 More specifically, this intriguing evolutionary theory rests on the evidence of common mechanistic pathways of response to changes in gut microbiome, that are shared by autoimmune and metabolic diseases. The use of broad-spectrum antibiotics—which are, basically, the fastest and most detrimental driver of dysbiosis—during early life has been identified as a risk factor for the later development of both early onset IBD2 and obesity/overweight,3 in human cohorts and in elegant mouse models.3 On the other side, the therapeutic modulation of gut microbiota, mainly faecal microbiota transplantation (FMT), has brought promising results in these settings, including UC4 and metabolic syndrome (MetS).5

Type 1 diabetes (T1D) represents an interesting …